fix: promote flower and pyenv-win to standalone entries

flower was a sub-entry under celery, pyenv-win under pyenv. Both are
standalone projects that deserve their own rows on the website.

Moved flower from Task Queues to Admin Panels since it is a monitoring
and web admin tool, not a task queue itself. Placed pyenv-win as a
top-level entry in Environment Management.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>